As far as I'm aware warlock pets are different from totems. I believe that attacking with a totem is actually treated as the shaman engaging the mob.

An easy way to prove this would be to get a totem to kill a mob without the shaman attacking it at all - if you can loot the mob, then I am correct. If a warlock's demon attacks and kills a mob without anyone else hitting it...then nobody gets to loot it as it's seen as the demon's kill.